Waiting 18 months between pregnancies reduces health risks to both mom and baby, according to extensive new research published in JAMA Internal Medicine.
"Our study found increased risks to both mother and infant when pregnancies are closely spaced, including for women older than 35," said lead author Laura Schummers in a statement. "The findings for older women are particularly important, as older women tend to more closely space their pregnancies and often do so intentionally."
Across the board, getting pregnant in less than 18 months after giving birth results in risky pregnancies for women of all ages. Mothers who were 35 or older saw risks to their personal health while women of all ages saw risks to the infant, the greatest being those aged 20 to 34.
To evaluate how pregnancy spacing can be impacted by a woman's age, researchers analyzed nearly 150,000 Canadian health records for mothers and babies including birth records, billing codes, hospitalization data, infertility information, and census records to find links between maternal mortality and severe morbidity, a rare but life-threatening complication of pregnancy, labor, and delivery. They found that intervals less than 18 months are associated with a higher risk of adverse pregnancy outcomes.
Mothers 35 and older who conceived six months after birth saw a 1.2 percent risk (12 cases per 1,000 pregnancies) of maternal mortality or severe morbidity and a 6 percent chance of giving birth prematurely. Waiting 18 months reduced that risk to just 0.5 percent and nearly halved, respectively.
Women aged 20 to 34 who conceived six months after giving birth saw an 8.5 percent risk of preterm birth delivery while those who waited 18 months saw their risk drop by nearly 5 percent.
The authors say their work confirms that there are different health risks for different age groups. The findings are especially helpful and encouraging for older mothers planning their families, however, the higher risk to younger women perhaps reflects a lack of information being utilized when it comes to family planning.
"Short pregnancy spacing might reflect unplanned pregnancies, particularly among young women," said Dr Sonia Hernandez-Diaz, professor of epidemiology at the Harvard T.H. Chan School of Public Health.
"Whether the elevated risks are due to our bodies not having time to recover if we conceive soon after delivering or to factors associated with unplanned pregnancies, like inadequate prenatal care, the recommendation might be the same: improve access to postpartum contraception, or abstain from unprotected sexual intercourse with a male partner following a birth."